U.S. Pat. No. 4,606,953 to Suzuki et al. (and DE 3422920) describes coatings for steel pipes, including successively a layer of epoxy resin, a layer of grafted polypropylene and finally an external layer of a mixture of polypropylene and of a polypropylene/polyethylene block copolymer. The glass transition temperature (T.sub.g) of the epoxy resin is between 80 and 94.degree. C. These coatings are suitable for hot water at 90.degree. C.
U.S. Pat. Re. No. 30,006 to Sakayori et al. describes coatings for steel pipes including successively an epoxy resin and a polyethylene modified by grafting or copolymerization with maleic anhydride. Nothing is written concerning the T.sub.g of the epoxy resin; however, the polyethylene does not make it possible to work above 80.degree. C. Thus, the prior art has not described any coating which has a high peel strength at 130.degree. C. like that of the invention.